1. Field of the Invention
The present invention relates to the structure of the front end of a side-view type endoscope which is provided with a treatment tool raising portion provided in the front end of the body thereof.
2. Description of the Related Art
In general, an endoscope includes an insertion portion which can be inserted in a human body and which is provided with a treatment tool insertion channel. When a treatment tool is inserted in the insertion channel, the front end thereof projects from the front end of the insertion portion of the endoscope.
In case of a side-view type endoscope which is adapted to view the lateral portion of the front end of the insertion portion thereof, as can be seen in FIG. 11, the front end body 1 of the endoscope is provided with a treatment tool (instrument) raising portion (raising piece) 3 which raises the projecting front end of the treatment tool toward the lateral portion of the front end body 1, so that the front end of the treatment tool is located around the center portion of the field of view.
The raising piece 3 is held in a receptacle groove 2 formed in the front end body 1. The raising piece 3 is made of stainless steel and is rotatable about an axis 8. The receptacle groove 2 opens at the front end and the opposed side portions. The raising piece 3 can be swung by a remote-control operation so that the treatment tool 6 disposed on the raising piece 3 protrudes in the forward and upward (oblique) direction or the lateral direction. Note that 4 designates the view window, and 5 the illumination window, respectively.
To prevent the distal end of the front end body 1 from coming into direct contact with a mucous membrane in a body cavity of a patient, possibly doing harm to the mucous membrane, the front end body 1 of the endoscope is surrounded by an end cap 30 which is attached to the front end body 1 and is detachable.
The end cap 30 is made of an elastic material and is provided, on the inner peripheral surface near the rear end thereof, with a small diameter annular portion 32 which projects toward the center axis thereof. When the annular projection 32 is fitted in a peripheral groove 7 formed on the outer peripheral surface of the front end body 1, the end cap 30 is connected to the front end body 1.
There is a possibility that the end cap 30 may be completely or partially disengaged from the front end body 1 when the front end body forcedly passes through a strictured portion within a body cavity during an examination using the endoscope.
Consequently, acute angle portions 2a of the receptacle groove 2 that are located on the front end surface of the metal front end body 1 are exposed and may be pressed onto the mucous membrane during the insertion of the endoscope or a suction operation, possibly causing harm to the mucous membrane. The same occurs when an operator (doctor) fails to attach the end cap 30 to the front end body 1 by mistake.
It is an object of the present invention to provide a front end structure of an endoscope in which there is no possibility that a mucous membrane or the like is harmed by a front end portion of a receptacle groove which receives therein a raising piece even if the end cap is accidentally disengaged from the front end body of the endoscope, or no end cap is attached to the front end body by mistake.